The present invention relates generally to ion sputtering cylindrical magnetrons utilized for coating substrate articles and, more specifically, to attachment apparatuses for affixing a cylindrical magnetron target to a target mounting spindle.
A major method for depositing a thin coating on large-surface-area substrates, such as computer monitor screens, architectural glass panels, automobile windshields, and the like is ion sputtering. The coating materials are deposited with a magnetron in a vacuum chamber upon the substrate utilizing reactive and/or inert gases and have been known in the art for some time. For example, a cylindrical target structure in a magnetron is described in Boozenny, et al., U.S. Pat. No. 5,096,562. The target structure employs a removable support spindle at each end of the cylindrical target structure. The support spindle at one end supplies and withdraws cooling fluid from within the cylinder that contains a driving mechanism for rotation. A second support spindle at the other end of the target structure contains an electrical power connection to the target surface. A more recent example of an attachment apparatus that affixes a rotatable cylindrical magnetron target to a support spindle is disclosed in Morgan, U.S. Pat. No. 5,591,314. The apparatus is used to releasably affix a rotating cylindrical magnetron target to a spindle utilizing a threaded spindle collar. The spindle collar engages threads on the outside surface of the target with a single water-to-vacuum seal located at the target and spindle interface. The threads may be removed from the target for repair and replacement.
However, there are some drawbacks to the currently known attachment devices affixing a rotatable cylindrical magnetron target to a support spindle. It is difficult to unscrew existing collar designs because the parts have become exposed to the sputtering process, the intense heating, and the coating build-up over the parts. Other problems arise when attempting to unscrew target collars by hammering with a spanner wrench to disengage the target. Additional problems are created by spindle run-out when there is imperfect parallelism between the target face and the spindle it is attached to. Cylindrical magnetron target repair and replacement can be a costly, time-consuming process in its large manufacturing plant environment.
Currently known attachment devices involve a costly, time-consuming repair process when removing the spindle from the target for significant reasons. It can be very difficult to access and to adjust the four loosening screws that are used to produce proper O-ring compression in the restricted space on the back of the spindle between the target and the end block from which the spindle protrudes. Secondly, problems are caused when unscrewing the collar from the end of the target by inserting a spanner nut wrench into the gap on the back of the spindle and into some holes in the collar. The spanner nut wrench is generally hit repeatedly with a hammer to get the collar to come loose and off. This hammering action can damage drive parts inside the end block and other drive-train components of the ion sputtering magnetron.
Thus, there is a need for new attachment apparatus between cylindrical target and spindles which eliminates those disadvantages.